Molybdenum-99 (Mo-99) is the radioactive parent of Technecium-99m (Tc-99m), a metastable radioisotope commonly used in medical procedures. Currently, the predominant production mechanism of molybdenum-99 is by fission of U-235, which produces a high-level waste (HLW) stream. Alternative, HLW-free mechanisms have been proposed, but most of these involve targets of isotopically-enriched molybdenum isotopes (e.g., 98Mo(n,g)99Mo or 100Mo(g,n)99Mo), and have two drawbacks. First, production of the isotopically enriched targets is expensive. Second, the Mo-99 material has very low specific activity, which complicates chemical extraction of the Tc-99m from the molybdenum parent material.
The only reactor in North America which produces Mo-99 is nearing the end of its life, and the United States finds itself relying more heavily on overseas suppliers for this important medical isotope. Technetium-99 is utilized in approximately 70% of all medical procedures in the US that involve medical isotopes. Thus, a critical need has arisen for economical Mo-99 production sources within North America, which preferably do not create a high-level waste stream.